Boxes or other containers are commonly tracked by attaching a bar code label or by printing a bar code directly on the box. The boxes are commonly moved by a conveyor belt or other transport along a predetermined path, where the bar codes are read and the leading edges of the boxes are detected. In one example, each box is deflected onto one of a plurality of locations depending upon the destination indicated by the bar code, or whether there is no bar code, when the leading edge of the box reaches a diverting device. In the prior art, a laser beam scanning source and reflection sensor had to be set up to read the bar codes, and a separate box detector had to be set up. The cost for the separate setups, whose relative positions might have to be accurately established, added to the cost of the box handling system. A box handling system that required less time and labor to set up the system, would be of value.
In accordance with one embodiment of the present invention, a system is provided, of a type that directs a scanning laser beam at bar codes on moving containers and that detects laser beam reflections for delivery to a bar code reader, which includes apparatus for detecting the containers at minimal additional cost. The apparatus for detecting each container includes a circuit having an input connected to the reflected laser beam sensor to receive the signals representing laser reflections from the containers. In addition to reading bar codes, the apparatus generates a xe2x80x9cbox-detectedxe2x80x9d signal when it detects a box whether or not the box has a readable bar code.
The container detecting circuit indicates detection of the container when the magnitude of the output from the laser reflection sensor increases from a low level representing no container, to above a predetermined level that represents reflections from a container. The container detecting circuit has a circuit part that ignores an increase in reflectance resulting from a bar code space element that follows a brief decrease from an adjacent bar code line element.